In this study, we observed about one in four infants born at full-term to mothers with SARS-CoV-2 during pregnancy were at risk for developmental delays determined by having at least one developmental domain below cut-off on ASQ®-3 screening at 16 to 18 months of age. Additionally, we observed no differences in outcomes between infants born to asymptomatic and mildly symptomatic mothers with SARS-CoV-2. These results highlight the urgent need for follow-up studies of infants born to mothers with SARS-CoV-2.
The literature on ASQ®-3 developmental screening of low-risk full-term infants show a positive screen in 12.6–13.6% children in at least one developmental domain (15, 17). In our study cohort, we observed that 24% of subjects were ‘below cutoff’ in at least one developmental domain and an additional 29% were ‘close to the cutoff’ in at least one domain, significantly more than what would be expected for a medically low-risk cohort of full-term infants without any genetic or congenital anomalies. These results are similar to preliminary evidence from other emerging epidemiological studies suggesting association of maternal SARS-CoV-2 with neurodevelopmental sequelae in some offspring (18). Edlow et al. observed greater rate of neurodevelopmental diagnoses in 222 infants born to SARS-CoV-2 positive mothers at 12 months of age after adjusting for multiple confounding factors including prematurity (adjusted OR 1.86, CI 1.03–3.36, P = .04), particularly during third-trimester maternal infection (18). However, their study relied on International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (ICD-10) diagnostic codes, which may lead to misclassification and lacks the sensitivity of a prospective neurodevelopmental screening such as in our study. Shuffrey and colleagues concluded in their study that birth during the pandemic and not in-utero exposure to maternal SARS-CoV-2 infection was associated with differences in neurodevelopment at 6 months of age (19). Both these studies had limited duration of follow-up until maximum one year of age, which may not yet identify risk in subjects on developmental screening assessment when compared to 16 to 18 months of age as performed in our study.
Similar to prior studies, we observed increased concerns in communication, fine motor, and problem-solving neurodevelopmental domains (19–21). Other than possibility of these findings being related to the effects on fetus from maternal immune response after SARS-CoV-2 infection, it could also possibly reflect societal and behavioral changes or stressors that occurred during COVID-19 pandemic resulting in these preliminary findings (21–24). Therefore, it would be important to differentiate impact of maternal immune activation to those from pandemic related effects on infant neurodevelopment in future studies.
In this cohort of mothers with asymptomatic or mild symptomatic infection, there was no difference in outcomes of their children due to symptomatic maternal status. Most symptomatic mothers with SARS-CoV-2 requiring respiratory support or intensive care delivered prematurely and therefore excluded from this study. However, national data suggests that vast majority of mothers with SARS-CoV-2 deliver at full-term and have asymptomatic or mild infection (25). Therefore, it is important to screen these infants in studies like ours from an epidemiological and public health perspective.
Our study has limitations. It has a small sample size from a single center. There is a possibility of ascertainment bias due to likelihood that parents who had concerns for development of their child were more likely to participate in the study, although standardized information was presented to parents while obtaining consent. There is absence of ideal comparable cohort of subjects who were born to mothers with negative SARS-CoV-2 testing during similar timeframe of pandemic as opposed to standardized ASQ®-3 historical averages. The added stressors during the pandemic of inconsistent childcare, food insecurity, job and housing losses could confound the risk of having further developmental delays (21–24). Finally, while ASQ®-3 is a validated questionnaire that can be administered virtually, however, it would be important to have follow up with in-person assessments to further identify degree of developmental delays.
Despite these limitations, it is clear that further research is warranted to study long-term effects on infants born to mothers with SARS-CoV-2 during pregnancy. Findings of this study add to the evidence of possible risk for neurodevelopmental delays in infants due to maternal COVID infection. Studies which follow these children will be important to document longer term neurodevelopmental problems in full-term infants (26, 27). While infants of mothers more severely affected and delivered prematurely are likely to be at increased risk for adverse neurodevelopmental outcomes, this study shows that the monitoring of infants whose mothers were asymptomatic or mildly symptomatic with SARS-CoV-2 infection and progressed to full-term for delivery is warranted as well.
In conclusion, we observed increased risk of neurodevelopmental delays during screening of infants born at full term to mothers with SARS-CoV-2 at 16 to 18 months of age. Additionally, we observed no difference in outcomes between infants born to asymptomatic and mildly symptomatic mothers with SARS-CoV-2. These results highlight the urgent need for follow up studies of infants born to mothers with SARS-CoV-2.